ABSTRACT
The paper carries out a review of influence exerted by subsurface microbiota on hard rocks in the underground space of megalopolises. It describes natural and technogenic conditions, in which the microbiota develops in the underground medium. Particular attention is given to factors, such as the presence of aquifers with different chemical composition and contamination level, natural occurrence of layers with organic matter in the rock section, urban sources of water-bearing strata contamination by organic and inorganic compounds, which serve as nutritious and energetic substrate for microorganisms. There is a notice of temperature and radiation effects on intensification of microbiological processes. It is pointed out that all types of hard-rock formations in geomechanical calculations of constructions stability should be considered as fractured-and-block medium, void content of which determines the degree of vulnerability to microbiological impact. Based on experimental research main directions of subsurface microbiota activity have been established and thoroughly studied. They include the impact of metabolism products (acids, enzymes, gases) on hard rocks, changes in aquifers redox and acid-base conditions, evolution of groundwater aggressiveness level, and transformation of stress-strain state of the stratum.
